Field
Embodiments of the present disclosure generally relate to solid oxide fuel cells (SOFCs) and, more specifically relate to a method of removing carbonaceous deposits in a liquid-hydrocarbon fueled solid oxide fuel cell and associated specially configured liquid-hydrocarbon fueled solid oxide fuel cell system.
Technical Background
As is conventionally known, a solid oxide fuel cell consists of three major parts; an anode, where electrochemical oxidation takes place, a cathode, where electrochemical reduction takes place and the electrolyte membrane, which is a dense, gas impermeable, ion transport membrane which exhibits purely ionic or mixed ionic-electronic conductivity at an elevated temperature range. Cathodes produce oxygen ions which then migrate through the electrolyte membranes to the anode electrode. The oxygen ions oxidize the fuel in the anode and thereby produce electrons, which flow through an external electrical circuit back to the cathode, thereby generating electrical energy.
Referring to FIG. 1, conventional solid oxide fuel cells 100 (SOFC), include an anode 120. The anode 120 is in contact with the solid oxide electrolyte 170 and may also be exposed to fuel (gas, liquid or solid), for example, a carbonaceous fuel 142. In the cathode 130, which performs O2 (g) reduction of the cathode metal in the presence of air 144 to yield oxygen ions 146, is placed on the opposing side of the solid oxide electrolyte 170. For current collection at the anode 120, a metal wire, or any other electron conducting material that is solid and inert at the operating conditions, may be electrically connected to the anode 120 to facilitate collection of the electrons which travel back to the cathode 130 via electrical circuit 150.
Referring again to FIG. 1, an electrochemical reaction converts fuel 142 and air 144 into electricity without combustion. A solid oxide fuel cell 100 is a high temperature fuel cell. At high temperature, warmed air 144 enters the solid oxide fuel cell 100 adjacent the cathode 130 and carbonaceous fuel 142 enters the solid oxide fuel cell 100 adjacent to the anode 120. Subsequently, a chemical reaction begins in the solid oxide fuel cell 100. As the fuel 142 crosses the anode 120, it attracts oxygen ions 146 from the cathode 130. The oxygen ions 146 combine with the fuel 142 to produce electricity and waste products 148 including water, and small amounts of carbon dioxide. As long as there is fuel 142, air 144, and heat, the process continues producing electricity. However, as the solid oxide fuel cell 100 operates the efficiency and/or power output diminishes over time.
Accordingly, ongoing needs exist for methods of improving the long-term efficiency and power output of solid oxide fuel cells 100 and for solid oxide fuel cell systems which maintain efficiency and power output over time.